This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The journal retracts the article “Artemisia Extracts and Artemisinin-Based Antimalarials for COVI... more The journal retracts the article “Artemisia Extracts and Artemisinin-Based Antimalarials for COVID-19 Management: Could These Be Effective Antivirals for COVID-19 Treatment [...]
The first part of the December 2018 edition is devoted to selected manuscripts (8) presented at B... more The first part of the December 2018 edition is devoted to selected manuscripts (8) presented at Bromo-2018. I am very grateful to Profs. Bambang Prajogo and Tutik Sri Wahyuni for extending an invitation to participate in this scientific meeting, as well as for organizing this issue. The editors join me in thanking Profs Prajogo and Wahyuni, the authors, and the reviewers for their efforts that have made this issue possible, and to the production department for putting it into print.
As the world desperately searches for ways to treat the coronavirus disease 2019 (COVID-19) pande... more As the world desperately searches for ways to treat the coronavirus disease 2019 (COVID-19) pandemic, a growing number of people are turning to herbal remedies. The Artemisia species, such as A. annua and A. afra, in particular, exhibit positive effects against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and COVID-19 related symptoms. A. annua is a source of artemisinin, which is active against malaria, and also exhibits potential for other diseases. This has increased interest in artemisinin’s potential for drug repurposing. Artemisinin-based combination therapies, so-called ACTs, have already been recognized as first-line treatments against malaria. Artemisia extract, as well as ACTs, have demonstrated inhibition of SARS-CoV-2. Artemisinin and its derivatives have also shown anti-inflammatory effects, including inhibition of interleukin-6 (IL-6) that plays a key role in the development of severe COVID-19. There is now sufficient evidence in the literatur...
13 C-NMR shift changes associated with deprotonation are measured for 15 phenols and 4 flavonoids... more 13 C-NMR shift changes associated with deprotonation are measured for 15 phenols and 4 flavonoids, leading to several corrections of literature reports. The additive shifts are useful for OH-group acidity determinations and I3 C signal assignments. The shielding variation associated with proton abstraction in phenols is of general interest with respect to the electron density distribution in these systems as well as for structure elucidation and IJC-NMR signal assignments in polyphenolic compounds. A recent publication on phenol deprotonation shifts' prompts us to report some measurements which, in agreement with earlier investigations 2 show deshielding at higher pH for the ipso and the ortho, and larger shielding only for the para carbon atom. Consequently, the direction of
The potential of one- and two-dimensional NMR techniques for the identification of individual sug... more The potential of one- and two-dimensional NMR techniques for the identification of individual sugar residues, their anomeric configuration, interglycosidic linkages, sequencing and the site of any appended group, in establishing the structures of naturally occurring oligosaccharides and glycosides is presented.
Page 1. '"c NMR Shifts and Substituted Indans' Conformations of Pawan Kumar Agrawa... more Page 1. '"c NMR Shifts and Substituted Indans' Conformations of Pawan Kumar Agrawal and Hans-Jorg Schneider* Fachrichtung 14.1 Organische Chemie der UniversitZt des Saarlandes, D 6600 Saarbrucken 11, FRG Mange1 ...
Page 1. MAGNETIC RESONANCE IN CHEMISTRY, VOL. 30, 1079-1083 (1992) Structure Establishment by Two... more Page 1. MAGNETIC RESONANCE IN CHEMISTRY, VOL. 30, 1079-1083 (1992) Structure Establishment by Two-Dimensional NMR Spectroscopy of the Product Obtained in the Reaction of MCPBA and Himachalol and revised 'H NMR Assignments for Himachalol* ~ ...
In continuation of our chemical investigation on Indian horse chestnuts, seeds of Aesculus indica... more In continuation of our chemical investigation on Indian horse chestnuts, seeds of Aesculus indica L. (Hippocastanaceae) (1 , 2) , we have now isolated two unsaturated and two saturated aliphatic esters, designated as compounds A, B, C, and D, from the CHCI, extract. Compound A, a viscous liquid, had ir
Page 1. MAGNETIC RESONANCE IN CHEMISTRY, VOL. 30, 1079-1083 (1992) Structure Establishment by Two... more Page 1. MAGNETIC RESONANCE IN CHEMISTRY, VOL. 30, 1079-1083 (1992) Structure Establishment by Two-Dimensional NMR Spectroscopy of the Product Obtained in the Reaction of MCPBA and Himachalol and revised 'H NMR Assignments for Himachalol* ~ ...
In continuation of our chemical investigation on Indian horse chestnuts, seeds of Aesculus indica... more In continuation of our chemical investigation on Indian horse chestnuts, seeds of Aesculus indica L. (Hippocastanaceae) (1 , 2) , we have now isolated two unsaturated and two saturated aliphatic esters, designated as compounds A, B, C, and D, from the CHCI, extract. Compound A, a viscous liquid, had ir
Naringenin, widely distributed in fruits and vegetables, is endowed with antiviral and other heal... more Naringenin, widely distributed in fruits and vegetables, is endowed with antiviral and other health beneficial activities, such as immune-stimulating and anti-inflammatory actions that could play a role in contributing, to some extent, to either preventing or alleviating coronavirus infection. Several computational studies have identified naringenin as one of the prominent flavonoids that can possibly inhibit internalization of the virus, virus-host interactions that trigger the cytokine storm, and replication of the virus. This review highlights the antiviral potential of naringenin in COVID-19 associated risk factors and its predicted therapeutic targets against SARS-CoV-2 infection.
A comparison of 1 H NMR chemical shifts for 25R and 25S spirostane-type steroidal sapogenins and ... more A comparison of 1 H NMR chemical shifts for 25R and 25S spirostane-type steroidal sapogenins and saponins suggest that orientation of 27-Me group has quite a different influence on chemical shifts of the methylene protonsoccupying β-and γ-positions, thus providing valuable information about the establishment 25R-and 25S-stereochemistry in these compounds.
Hesperidin and hesperetin are flavonoids that are abundantly present as constituents of citrus fr... more Hesperidin and hesperetin are flavonoids that are abundantly present as constituents of citrus fruits. These compounds have attracted attention as several computational methods, mostly docking studies, have shown that hesperidin may bind to multiple regions of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (spike protein, angiotensin-converting enzyme 2, and proteases). Hesperidin has a low binding energy, both with the SARS-CoV-2 “spike” protein responsible for internalization, and also with the “PLpro” and “Mpro” responsible for transforming the early proteins of the virus into the complex responsible for viral replication. This suggests that these flavonoids could act as prophylactic agents by blocking several mechanisms of viral infection and replication, and thus helping the host cell to resist viral attack.
Quercetin, a naturally occurring dietary flavonoid, is well known to ameliorate chronic diseases ... more Quercetin, a naturally occurring dietary flavonoid, is well known to ameliorate chronic diseases and aging processes in humans, and its antiviral properties have been investigated in numerous studies. In silico and in vitro studies demonstrated that quercetin can interfere with various stages of the coronavirus entry and replication cycle such as PLpro, 3CLpro, and NTPase/helicase. Due to its pleiotropic activities and lack of systemic toxicity, quercetin and its derivatives may represent target compounds to be tested in future clinical trials to enrich the drug arsenal against coronavirus infections. There is evidence that quercetin in combination with, for example, vitamins C and D, may exert a synergistic antiviral action that may provide either an alternative or additional therapeutic/preventive option due to overlapping antiviral and immunomodulatory properties. This review summarizes the antiviral significance of quercetin and proposes a possible strategy for the effective uti...
Various computational studies, including in silico ones, have identified several existing compoun... more Various computational studies, including in silico ones, have identified several existing compounds that could serve as effective inhibitors of the SARS-CoV-2 main protease (Mpro), and thus preventing replication of the virus. Among these, rutin has been identified as a potential hit, having prominent binding affinity to the virus. Moreover, its presence in several traditional antiviral medicines prescribed in China to infected patients with mild to moderate symptoms of COVID-19 justify its promise as a repurposed bioactive secondary metabolite against SARS-CoV-2.
The 13C NMR resonances corresponding to the C-Me group of C-6 and/or C-8 C-methylated-flavonoids ... more The 13C NMR resonances corresponding to the C-Me group of C-6 and/or C-8 C-methylated-flavonoids absorb between 6.7–10.0 ppm and typically between 6.7–8.7 ppm. A comparative 13C NMR study reflects that the 13C NMR chemical shifts reported for 6-hydroxy-5-methyl-3′,4′,5′-trimethoxyaurone-4-O-α-L-rhamnoside from Pterocarpus santalinus and 8-C-methyl-5,7,2′,4′- tetramethoxyflavanone from Terminalia alata are inconsistent with the assigned structures, and therefore need reconsideration.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The journal retracts the article “Artemisia Extracts and Artemisinin-Based Antimalarials for COVI... more The journal retracts the article “Artemisia Extracts and Artemisinin-Based Antimalarials for COVID-19 Management: Could These Be Effective Antivirals for COVID-19 Treatment [...]
The first part of the December 2018 edition is devoted to selected manuscripts (8) presented at B... more The first part of the December 2018 edition is devoted to selected manuscripts (8) presented at Bromo-2018. I am very grateful to Profs. Bambang Prajogo and Tutik Sri Wahyuni for extending an invitation to participate in this scientific meeting, as well as for organizing this issue. The editors join me in thanking Profs Prajogo and Wahyuni, the authors, and the reviewers for their efforts that have made this issue possible, and to the production department for putting it into print.
As the world desperately searches for ways to treat the coronavirus disease 2019 (COVID-19) pande... more As the world desperately searches for ways to treat the coronavirus disease 2019 (COVID-19) pandemic, a growing number of people are turning to herbal remedies. The Artemisia species, such as A. annua and A. afra, in particular, exhibit positive effects against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and COVID-19 related symptoms. A. annua is a source of artemisinin, which is active against malaria, and also exhibits potential for other diseases. This has increased interest in artemisinin’s potential for drug repurposing. Artemisinin-based combination therapies, so-called ACTs, have already been recognized as first-line treatments against malaria. Artemisia extract, as well as ACTs, have demonstrated inhibition of SARS-CoV-2. Artemisinin and its derivatives have also shown anti-inflammatory effects, including inhibition of interleukin-6 (IL-6) that plays a key role in the development of severe COVID-19. There is now sufficient evidence in the literatur...
13 C-NMR shift changes associated with deprotonation are measured for 15 phenols and 4 flavonoids... more 13 C-NMR shift changes associated with deprotonation are measured for 15 phenols and 4 flavonoids, leading to several corrections of literature reports. The additive shifts are useful for OH-group acidity determinations and I3 C signal assignments. The shielding variation associated with proton abstraction in phenols is of general interest with respect to the electron density distribution in these systems as well as for structure elucidation and IJC-NMR signal assignments in polyphenolic compounds. A recent publication on phenol deprotonation shifts' prompts us to report some measurements which, in agreement with earlier investigations 2 show deshielding at higher pH for the ipso and the ortho, and larger shielding only for the para carbon atom. Consequently, the direction of
The potential of one- and two-dimensional NMR techniques for the identification of individual sug... more The potential of one- and two-dimensional NMR techniques for the identification of individual sugar residues, their anomeric configuration, interglycosidic linkages, sequencing and the site of any appended group, in establishing the structures of naturally occurring oligosaccharides and glycosides is presented.
Page 1. '"c NMR Shifts and Substituted Indans' Conformations of Pawan Kumar Agrawa... more Page 1. '"c NMR Shifts and Substituted Indans' Conformations of Pawan Kumar Agrawal and Hans-Jorg Schneider* Fachrichtung 14.1 Organische Chemie der UniversitZt des Saarlandes, D 6600 Saarbrucken 11, FRG Mange1 ...
Page 1. MAGNETIC RESONANCE IN CHEMISTRY, VOL. 30, 1079-1083 (1992) Structure Establishment by Two... more Page 1. MAGNETIC RESONANCE IN CHEMISTRY, VOL. 30, 1079-1083 (1992) Structure Establishment by Two-Dimensional NMR Spectroscopy of the Product Obtained in the Reaction of MCPBA and Himachalol and revised 'H NMR Assignments for Himachalol* ~ ...
In continuation of our chemical investigation on Indian horse chestnuts, seeds of Aesculus indica... more In continuation of our chemical investigation on Indian horse chestnuts, seeds of Aesculus indica L. (Hippocastanaceae) (1 , 2) , we have now isolated two unsaturated and two saturated aliphatic esters, designated as compounds A, B, C, and D, from the CHCI, extract. Compound A, a viscous liquid, had ir
Page 1. MAGNETIC RESONANCE IN CHEMISTRY, VOL. 30, 1079-1083 (1992) Structure Establishment by Two... more Page 1. MAGNETIC RESONANCE IN CHEMISTRY, VOL. 30, 1079-1083 (1992) Structure Establishment by Two-Dimensional NMR Spectroscopy of the Product Obtained in the Reaction of MCPBA and Himachalol and revised 'H NMR Assignments for Himachalol* ~ ...
In continuation of our chemical investigation on Indian horse chestnuts, seeds of Aesculus indica... more In continuation of our chemical investigation on Indian horse chestnuts, seeds of Aesculus indica L. (Hippocastanaceae) (1 , 2) , we have now isolated two unsaturated and two saturated aliphatic esters, designated as compounds A, B, C, and D, from the CHCI, extract. Compound A, a viscous liquid, had ir
Naringenin, widely distributed in fruits and vegetables, is endowed with antiviral and other heal... more Naringenin, widely distributed in fruits and vegetables, is endowed with antiviral and other health beneficial activities, such as immune-stimulating and anti-inflammatory actions that could play a role in contributing, to some extent, to either preventing or alleviating coronavirus infection. Several computational studies have identified naringenin as one of the prominent flavonoids that can possibly inhibit internalization of the virus, virus-host interactions that trigger the cytokine storm, and replication of the virus. This review highlights the antiviral potential of naringenin in COVID-19 associated risk factors and its predicted therapeutic targets against SARS-CoV-2 infection.
A comparison of 1 H NMR chemical shifts for 25R and 25S spirostane-type steroidal sapogenins and ... more A comparison of 1 H NMR chemical shifts for 25R and 25S spirostane-type steroidal sapogenins and saponins suggest that orientation of 27-Me group has quite a different influence on chemical shifts of the methylene protonsoccupying β-and γ-positions, thus providing valuable information about the establishment 25R-and 25S-stereochemistry in these compounds.
Hesperidin and hesperetin are flavonoids that are abundantly present as constituents of citrus fr... more Hesperidin and hesperetin are flavonoids that are abundantly present as constituents of citrus fruits. These compounds have attracted attention as several computational methods, mostly docking studies, have shown that hesperidin may bind to multiple regions of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (spike protein, angiotensin-converting enzyme 2, and proteases). Hesperidin has a low binding energy, both with the SARS-CoV-2 “spike” protein responsible for internalization, and also with the “PLpro” and “Mpro” responsible for transforming the early proteins of the virus into the complex responsible for viral replication. This suggests that these flavonoids could act as prophylactic agents by blocking several mechanisms of viral infection and replication, and thus helping the host cell to resist viral attack.
Quercetin, a naturally occurring dietary flavonoid, is well known to ameliorate chronic diseases ... more Quercetin, a naturally occurring dietary flavonoid, is well known to ameliorate chronic diseases and aging processes in humans, and its antiviral properties have been investigated in numerous studies. In silico and in vitro studies demonstrated that quercetin can interfere with various stages of the coronavirus entry and replication cycle such as PLpro, 3CLpro, and NTPase/helicase. Due to its pleiotropic activities and lack of systemic toxicity, quercetin and its derivatives may represent target compounds to be tested in future clinical trials to enrich the drug arsenal against coronavirus infections. There is evidence that quercetin in combination with, for example, vitamins C and D, may exert a synergistic antiviral action that may provide either an alternative or additional therapeutic/preventive option due to overlapping antiviral and immunomodulatory properties. This review summarizes the antiviral significance of quercetin and proposes a possible strategy for the effective uti...
Various computational studies, including in silico ones, have identified several existing compoun... more Various computational studies, including in silico ones, have identified several existing compounds that could serve as effective inhibitors of the SARS-CoV-2 main protease (Mpro), and thus preventing replication of the virus. Among these, rutin has been identified as a potential hit, having prominent binding affinity to the virus. Moreover, its presence in several traditional antiviral medicines prescribed in China to infected patients with mild to moderate symptoms of COVID-19 justify its promise as a repurposed bioactive secondary metabolite against SARS-CoV-2.
The 13C NMR resonances corresponding to the C-Me group of C-6 and/or C-8 C-methylated-flavonoids ... more The 13C NMR resonances corresponding to the C-Me group of C-6 and/or C-8 C-methylated-flavonoids absorb between 6.7–10.0 ppm and typically between 6.7–8.7 ppm. A comparative 13C NMR study reflects that the 13C NMR chemical shifts reported for 6-hydroxy-5-methyl-3′,4′,5′-trimethoxyaurone-4-O-α-L-rhamnoside from Pterocarpus santalinus and 8-C-methyl-5,7,2′,4′- tetramethoxyflavanone from Terminalia alata are inconsistent with the assigned structures, and therefore need reconsideration.
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